Korean Journal of Thoracic and Cardiovascular Surgery 2018; 51(6): 390-394  https://doi.org/10.5090/kjtcs.2018.51.6.390
Use of an Optical Scanning Device to Monitor the Progress of Noninvasive Treatments for Chest Wall Deformity: A Pilot Study
Robert E. Kelly1,2,3, Robert J. Obermeyer1,2, M. Ann Kuhn1,2, Frazier W. Frantz1,2, Mohammad F. Obeid3, Nahom Kidane3, and Frederic D. McKenzie2,3
1Department of Surgery and Pediatrics, Children’s Hospital of The King’s Daughters, 2Department of Surgery and Pediatrics, Eastern Virginia Medical School, 3Department of Modeling and Simulation Engineering, Batten College of Engineering and Technology, Old Dominion University
Corresponding author: Robert E. Kelly Jr., Department of Surgery and Pediatrics, Children’s Hospital of The King’s Daughters, 601 Children’s Lane, Norfolk, VA, 23507 USA, (Tel) 1-757-668-7750, (Fax) 1-757-668-8860, (E-mail) Robert.Kelly@chkd.org
Received: July 12, 2018; Revised: October 13, 2018; Accepted: October 16, 2018.; Published online: December 5, 2018.
© The Korean Journal of Thoracic and Cardiovascular Surgery. All rights reserved.

cc This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract

Background

The nonsurgical treatment of chest wall deformity by a vacuum bell or external brace is gradual, with correction taking place over months. Monitoring the progress of nonsurgical treatment of chest wall deformity has relied on the ancient methods of measuring the depth of the excavatum and the protrusion of the carinatum. Patients, who are often adolescent, may become discouraged and abandon treatment.

Methods

Optical scanning was utilized before and after the intervention to assess the effectiveness of treatment. The device measured the change in chest shape at each visit. In this pilot study, patients were included if they were willing to undergo scanning before and after treatment. Both surgical and nonsurgical treatment results were assessed.

Results

Scanning was successful in 7 patients. Optical scanning allowed a visually clear, precise assessment of treatment, whether by operation, vacuum bell (for pectus excavatum), or external compression brace (for pectus carinatum). Millimeter-scale differences were identified and presented graphically to patients and families.

Conclusion

Optical scanning with the digital subtraction of images obtained months apart allows a comparison of chest shape before and after treatment. For nonsurgical, gradual methods, this allows the patient to more easily appreciate progress. We speculate that this will increase adherence to these methods in adolescent patients.

Keywords: Imaging, Funnel chest, Pectus carinatum
Introduction

Recently, vacuum bell therapy for pectus excavatum and external brace treatment for pectus carinatum have gained acceptance as nonsurgical treatments of chest wall deformity. It has proven difficult to monitor the progress of treatment. External measurements of the chest can be made using ruler or caliper devices, but these give a limited picture of the entire chest shape. Computed tomography scanning, which gives a good 3-dimensional (3D) picture with reconstruction, subjects the patient to ionizing radiation. Magnetic resonance imaging is expensive and time-consuming. We sought a noninvasive way to follow the progress of treatment and to provide positive reinforcement to adolescent patients who grow tired of the treatment, which often takes more than a year of daily application.

Methods

An optical scanner was developed from a Kinect device by the engineering department at Old Dominion University (Fig. 1). The equipment was verified to measure distances from the probe accurately, and its ability to produce a 3D image was confirmed [1,2]. Measurements of accuracy and precision were made, and were found to be more than sufficient for use in a biological system [37]. The scanner was used on both male and female patients without breast development, obtaining images in the supine position, with a consistent position relative to the scanner. A total of 7 adolescent male patients, aged 9 to 18 years, were studied. The scanner utilized visible light, not ionizing radiation. It was used in the examination room of our clinic.

Patients were scanned before, during, and after treatment. Photographs were taken at the beginning and end of treatment. Measurements were taken with a dowel and ruler for the excavatum patients. A color map, using the colors that make up visible light, was used to indicate where the chest had changed in shape. This image, which demonstrated treatment progress, was then shown to patients and parents to encourage adherence to the treatment regimen. Formal patient satisfaction surveys were not utilized.

This study was approved by the Institutional Review Board of the Eastern Virginia Medical School (IRB approval no., #14-10-EX-0214-CHKD).

Results

The device was utilized successfully in all patients. A male patient who underwent the Nuss procedure for the surgical treatment of pectus excavatum was studied. This patient, who was 18 years old at the time of the operation, had a Haller index of 5.7 and a correction index of 34%. He showed a clinically normal chest. In scans taken 1 week apart (before and after the operation), the chest wall was seen to be elevated by almost 2 cm (Fig. 2).

Vacuum bell treatment: A vacuum bell was applied twice daily by the patient or the patient’s parents, starting at 20 minutes each time and increasing to 2 hours twice daily (Figs. 37).

Pectus carinatum is routinely treated with an external brace (Figs. 810).

Discussion

This technique produced images that were well-received by patients and their families. The positive feedback of an objective demonstration of improvement is especially valuable for the vacuum bell and brace treatments, which change the chest shape slowly. A daily exam in the mirror performed by the patient may not make the same impression on young patients, who are impatient for results.

We scanned the patients in the supine position, which is a reproducible position. Changes in the anterior chest due to spine flexion or rotation were minimized. Breast protrusion in adolescent patients with developing breast tissue is a technical challenge that remains unresolved.

In conclusion, optical scanning offers a low-risk, practical, immediate, inexpensive, and well-accepted way to follow nonsurgical treatment of chest wall deformity.

Conflict of interest

No potential conflict of interest relevant to this article was reported. Drs. Kelly and Obermeyer are consultants for Zimmer-Biomet Inc., USA.

Acknowledgments

The authors gratefully acknowledge the technical assistance of Mrs. Kristina Laws and Mr. Antarius Daniel, and the manuscript preparation assistance of Mrs. Trisha Arnel.

Figures
Fig. 1. ODU scanner, showing a laptop containing our proprietary software and markings on the exam table to allow consistent patient placement in the supine position.
Fig. 2. Digital subtraction image of the chest contour before and after surgical correction in an 18-year-old male patient, showing elevation of the deepest part of the depression by 18.7 mm, and the surrounding areas by correspondingly smaller amounts.
Fig. 3. Vacuum bell (designed and manufactured by Eckhart Klobe in Germany).
Fig. 4. Digital subtraction of the chest contour before and after vacuum bell treatment of pectus excavatum over a 13-month period in a 15-year-old male. The deepest area was elevated by 11 mm; the surrounding areas were also elevated, so that the chest approached a normal shape.
Fig. 5. Digital subtraction image before and after 11 months of treatment of a 9-year-old male patient, showing elevation of a diffuse area of the central chest (in blue), and depression (normalization) of an adjacent area (in red and orange).
Fig. 6. Digital subtraction image before and after 9 months of vacuum bell treatment in a 13-year-old male, showing elevation of a diffuse area of the deepest portion (in blue), with flattening of adjacent areas in the left chest wall (in orange and yellow).
Fig. 7. Digital subtraction of the chest contour over a 12-month period, during which a 15-year-old male patient did not wear the vacuum bell as directed. The chest is objectively worse: the deepest part is about 10 mm deeper (in orange/red). Such an image facilitates a decision to change treatment.
Fig. 8. External brace used for the treatment of pectus carinatum (FMF; Pampamed Inc., Buenos Aires, Argentina).
Fig. 9. Digital subtraction of the chest contour before and after brace treatment for pectus carinatum over 9 months in a 14-year-old. This image shows flattening of the protrusion (in orange/red), which was resolved clinically.
Fig. 10. Digital subtraction of the chest contour before and after 1 month of external brace treatment of pectus carinatum in a 12-year-old male, showing good progress in treatment of the protrusion (in orange and red).
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